Chapter 12 Forensic Entomology

Case study – Bugs Don’t Lie 1. When did the children go missing? 2. When were the bodies found? 3. List 5 reasons for suspecting the stepfather. 4. Summarize the entomological evidence and explain how this lead to estimating the time of death.

Introduction O Forensic entomology – use of insects in legal investigations O Phylum Arthropoda – insects, spiders, scorpions, crayfish, and millipedes - invertebrates - externally segmented bodies - exoskeleton made of chitin

Historical Development O Fig p. 344 O 1 st documented use of insect evidence to solve crime  China in 1235

Insects and Forensics O Head – brain, antennae, eyes, and mouthparts O Thorax – 3 prs. of legs and possibly 2 prs of wings O Abdomen – reproductive and digestive organs O 29 orders of insects – flies and beetles most important to forensics

Insect Orders O Flies – Diptera O - found in almost every environment O ex) blowflies – found at 1 st stages of decomposition O Lay eggs in body openings  bloated stage the eggs hatch into maggots  move away from body to pupate  beetles move in and continue decay process

Insect Orders O Beetles – Coleoptera O - most prominent in later stages of decomposition O Final stage = skeletal – beetles are joined by other soil-dwelling insects O See Fig p. 346

Insects at Work O Life cycle – egg  larva(feeding stage)  pupa(relatively inactive, nonfeeding stage) O Abiotic and biotic factors  interact to maintain balance in an ecosystem O AF = sun, atmosphere, weather O BF = organisms or remains of organisms

There is strength in numbers O 1 million species of insects O Short lifespan but produce large numbers of eggs O Contribution to ecosystem = loosening of soil, pollination, consuming plant pests O Incomplete metamorphosis – nymph(wingless)  molts several times  adult O Meteorology vs climatology

Postmortem Interval(PMI) O Need to establish timeline of events O PMI is an important element of that timeline O crime-scene-creatures/interactive- determine-the-time-of-death/4390/

Collecting and Preserving Entomological Evidence O Include info about rainfall and temperature O Investigation team collects evidence and sends it to the forensic entomologist at the lab O 1. Start collection several feet away from the body O 2. measure distance between insect evidence and body O 3. collect samples at all stages on, near, or under body O 4. at lab – raise samples at same conditions as crime scene

What to record O 1. temperature O 2. type and amount of precipitation O 3. type and amount of light O 4. humidity O 5. amount and direction of wind

Temperature O An increase in temperature = an increase in insect development O A)ambient - 1 and 4 feet above the body O B) soil – surface, 10 cm. below surface, and 20 cm below surface

More on collecting and preserving evidence O Nets for flying stage O Pinned or transferred to vial in 80%alcohol O Take of largest larvae O Vials labeled inside and out using pencil O a) case # O b) collection time O c) date O d) geographic location O e) location of insects on victim O f) initials of investigator